namespace Chaos.NaCl.Internal.Ed25519Ref10;

internal static partial class FieldOperations
{
    /*
    return 1 if f is in {1,3,5,...,q-2}
    return 0 if f is in {0,2,4,...,q-1}

    Preconditions:
    |f| bounded by 1.1*2^26,1.1*2^25,1.1*2^26,1.1*2^25,etc.
    */
    //int fe_isnegative(const fe f)
    public static int fe_isnegative(ref FieldElement f)
    {
        FieldElement fr;
        fe_reduce(out fr, ref f);
        return fr.x0 & 1;
    }
}